In a saucepan, combine water, sugar, salt, corn syrup and lemon juice. Bring to a boil. Combine the cornstarch and water. Blend thoroughly. Add frozen boysenberries. Pour both mixtures into unbaked 9 inch pie crust. Cover with second top crust and seal well around the edges. Make several slashes in the top to release steam. Bake in a preheated 400 degree oven for 40 minutes until top is golden brown. Cool on a rack.